If I remember correctly this is a highly popular suggestion, ad it would be absolutely a killer feature for SpaceEngine, but it's an exceedingly hard task to accomplish. I'll post a link here from the old forum with an answer of SpaceEngineer regarding this possibility.It's dated back in 2012, but I'm sure enough that the answer is still valid, sorry.

Too sad, the beauty we can seen in most of astronomical pictures are just invisible (or near invisible) in the visible spectrum.

I think that's something that can be accomplished by modding : if we use some kind of layered/parallel-universe (let call that instances), we could create an instance per spectral domain. What's mostly missing here is the ability to switch from an instance of the universe to an other.

An extreamly big and hard job. You cant just invent that universe , it must be based in real observations took in several wavelenths like gamma , xray ,ultraviolet, infrarred, microwave , radio long and short (at least) . And all of them also made with very diferent kind of instruments and catalogs for that wavelenth (probably they will be really poor because that mesaurements are specific to analize some phenomenas)

I don't think so, if it's hard to implement for the developer, it is a thousand times harder for a modder.Also, even if someone tried, it would be such a fake effect it would be very un-appealing for most of users

The universe is not required to be in perfect harmony with human ambition.

What if it could be implemented in a sort of object based telescope mode that would link to a picture of the object online in the desired spectrum? That could at least work for cataloged objects? Just a thought, because that would be cool. But yes a massive undertaking as proposed that certainly would take time away from more important progress atm. Like the concept though. Especially for nebula.

Vice versa, catalog objects are harder to do with different wavelength. Earth textures takes 7 GB in visible spectrum. If we would adding 5 other bands, where we would take a global IR, UV, ... maps of the whole Earth? I don't think those exists. And there are other planets and moons...For procedural planets SE can generate texture maps. But this requires huge research work, read a lot of papers regarding propertied of planets and their atmospheres at different wavelengths. Each time user switches to another band it will must wait until SE reloads textures. Stars are the most easy to do: they are emitting a black body spectrum, it can be easily re-calculated to other wavelengths. Star corona is a different task: it emits a lot of non-thermal radio emission, as well ass gas giant magnetosphere. Galaxy dust probably also easy to do - thermal emission in IR. Nebulae are harder: they emits non-thermal emission.Radio frequencies also will need some blurring, strongly depending on a receiver aperture. Emitting objects must have blurry edges; if object is smaller than wavelength, it will be transparent or invisible. Diffraction and interference effects are strong at those radio wavelengths, I even don't know how to implement them, except ray-tracing (or wave propagation simulation?) Gamma ray, in opposite, are highly penetrative, solid bodies like planets will have a "transparent" upper layers, what is not easy to render.

Maybe the best way to start a multi-spectrum addon in space engine was to start only with ultraviolet and infrared, because they are easier to manage than other wavelength, mainly infrared and because they are the most similar to visible light. Start with stars, gas dusts, nebulae and finally planets. For planets with their own textures like Earth, because textures tend to be big in Mb, textures with lower resolution (2048x1024 to 512x256) would be the best solution. Proposed wavelengths: near ultraviolet, near infrared and thermal infrared.